1. Field of Invention
The present invention relates to a navigation apparatus.
2. Description of Related Art
In a conventional navigation apparatus for use on a vehicle such as a car, if a user or a driver of the vehicle sets a destination by operating an input unit, the current position of the vehicle detected by a current position detector is set as a starting point, a route from the starting point to the destination is searched for, and route navigation/guidance is performed along a route detected in the searching process. In the above route searching process, a route that is the shortest in distance from the starting point to the destination or a route that is the shortest in time needed to reach the destination is selected.
However, in general, in the route searching process, roads having a rather large width are preferentially selected, and actual traffic conditions such as traffic congestion or driving ease on roads are not taken into account. Thus, the selected route is not necessarily a route that is the shortest in time needed to reach the destination. Furthermore, users' preferences (such as that for a route including a smallest number of turns that cross oncoming traffic) are not reflected in the selection of the navigation route. To alleviate the above problems, it has been proposed to register routes corresponding to a starting point and a destination in storage means and reduce the search cost of the registered routes. Another known technique is to record previously traveled routes in a storage means and employ a part or whole of a recorded route in searching for a route when an input starting point and an input destination is on the recorded route (a specific example of this technique may be found, for example, in Japanese Unexamined Patent Application Publication No. 2000-9482).
By using techniques in which previously traveled routes are reflected in route selection, it is possible to select a route that is shortest in travel time or a route that meets a user's particular preference.